[ZODB-Dev] Re: BTrees strangeness (was [Zope-dev] Zope 2.X BIG Session problems - blocker - our site dies - need help of experience Zope developer, please)

[Toby Dickenson]

On Friday 05 March 2004 00:56, Chris McDonough wrote:
> On Thu, 2004-03-04 at 17:18, Casey Duncan wrote:

> > > What I'm unsure about is whether pack would keep recent revisions to
> > > unreferenced objects,
> > 
> > It won't.  A pack will now destroy anything unreferenced.

Thats true for the reference-counted BDB storages. (And in theory its 
dangerous.... There are some corner cases where these unreferenced objects 
can get written by normal ZODB usage). Unless I missed a recent change, 
FileStorage will keep all the objects modified within the pack window. But 
not their sub-objects.

> > I was thinking it could be an option in a normal pack to not remove
> > objects that were modified within the pack window even if they aren't
> > reachable. What I hadn't considered though are persistent subobjects.
> > Dealing with those would make it more complex in the general pack.
>
> Right.  It's not really a pack operation, although like a pack it may
> need to operate on all the objects in the database.

Thats how DirectoryStorage's pack works as standard.

-- 
Toby Dickenson